The present invention relates to thermal printers, and is particular directed to a thermal printer apparatus including a thermal print head and a print platen movable relative to each other.
A typical known thermal printer includes a print platen which does not move towards and away from the plane of a sheet being printed on. The thermal printer further includes a thermal print head which is movable towards and away from the print platen and also movable up and down relative to the print platen. Initially, a sheet feeder transports a sheet to be printed on to a printing position along a sheet feed path. When the sheet is at the printing position, the print head is controlled to move into contact with one side of the sheet. The print platen is usually already in contact with the opposite side of the sheet. When the print platen and the print head are contacting the sides of the sheet, thermal elements on the print head are controlled in a known manner to print information onto the sheet.
After printing information onto the sheet, the print head is moved away from the one side of the sheet. The sheet feeder then transports the sheet to a different position before the print head moves back into contact with the one side of the sheet to print other information onto the sheet. This cycle is repeated until all desired information is printed onto the sheet. After all desired information is printed onto the sheet, the sheet feeder transports that sheet out of the printing position. A disadvantage in using known print platens and print heads to print information onto sheets moving along the sheet feed path is that print quality may not always be consistent, especially when the sheet feeder feeds sheets into and out of the printing position along the sheet feed path at a relatively high rate.